Mites on taricha torosa

[ian]

I recently bought three Taricha torosa ,two are fine the third has lumps and bumps on his tail and a few on his back , i am sure they are mites. I have heard they are pretty difficult to get rid of but one method is to chill the newt to kill the mites . My question is what sort of temps can they safely go down to or is there another method anyone has used to get shot.